How much are you willing to spend? (Leather bags, or synthetic leather?)
For real leather, check here,
Leatherneck Jim's ,
or here
Fox Creek Leather .
For life of the biker warranty with no fuss or maintenance, try here
Willie and Max .
I've never shied away from maintaining leather goods, as in boots and belts (Mink Oil, Neet's foot oil, etc.), but it depends on what you are after and how you intend to use these bags. You can invest a lot of $$$ into them, but some will take care of YOU better than others.